This application claims the priority of Japanese Patent Application No. 6-266387 filed on Oct. 5, 1994 and PCT Application No. PCT/JP95/02047 filed on Oct. 5, 1995, the disclosures of which are expressly incorporated by reference herein.
The present invention relates to a rotary piston type internal combustion engine configured to rotate a rotor as a rotary piston provided in a cylindrical rotor holding bore in a housing, coaxially with a rotating axial center of the rotor holding bore.
A conventional reciprocating internal combustion engine converts reciprocating motion of a piston into rotating motion via a crank mechanism. However, presumably, due to the characteristics of the crank mechanism, approximately 50 to 60 percent of combustion gas pressure exerted on the piston is converted into output torque of the crank shaft.
Due to a valve over-lap period in which both the intake valve and exhaust valve are opened, even after exhaust is released, a small amount of combustion gas remains in the combustion chamber, and therefore it is difficult to improve the combustibility and also difficult to decrease the amount of unburned gas. The structure of the crank mechanism and valve driving mechanism including the intake valve and the exhaust valve is complex and it is therefore not easy to decrease vibration and noises caused by reciprocating motion of the piston. It is also difficult to revise the size of the four phase cycle reciprocating engine without decreasing the horsepower of the output. Accordingly, until present, various kinds of rotary piston type internal combustion engines (rotary piston engines) have been proposed. The rotary piston engine is classified either as a single rotation type rotary piston engine having a rotor rotating not eccentrically (i.e. rotating coaxially), or as a planetary rotation type rotary piston engine. As the structure of the former is more complex than that of the latter, the former has generally not been put into practical use. However, the Wankel rotary piston engine, an example of the latter type has been put into practical use.
In the Wankel rotary piston engine, a triangular rotor is held within a rotor holding bore which has an inner surface similar to a peritrocoid curve. The rotor is rotated in a planetary motion through the engaging of a rotor gear on the rotor with a gear on an eccentric output shaft. Depending on the planetary motion of the rotor, while three chambers outside of the rotor varying their capacities, four strokes of intake (suction), compression, combustion (expansion) and exhaust are performed. However, in this Wankel engine, the combustion gas pressure received by the trailing side portion of the pressure reception rotor surface facing to the combustion chamber exerts on the rotor so as to drive in reverse. Therefore, presumably, only approximately 60 to 70 percent of the combustion gas pressure received by the rotor can be converted into output torque. As well, it is also difficult to improve the combustibility in the combustion stroke and to decrease the exhaust quantity of unburned gases. Until present, various types of single rotation rotary piston engines have been proposed. FIGS. 51-56 show well known single rotation rotary engines 300A-300F. FIG. 57 shows a single rotation rotary engine 300G put into practical use by Malorie CO. This engine 300G has a housing 300, a rotor 301, a suction port 302, an ignition plug 303, an exhaust port 304 and a scavenging port 305, and the rotor 301 rotates clockwise. The engine 300H shown in FIG. 58 is provided with a housing 310, a suction port 311, an exhaust port 312, a rotor holding bore 313, a rotor 314 coaxial with the bore 313, cycloid tooth portions 315, 316 formed on the rotor 314, a first small cylindrical driven rotor 317, a second small cylindrical driven rotor 318, a combustion subchamber 319, an ignition plug 320 and the like. As shown in the chain lines, this engine 300H has a suction chamber 321, a compression chamber 322, an expansion chamber 323 and an exhaust chamber 324. A prototype of this engine 300H made in about 1945 was reported to have high output horse power performance notwithstanding its small and light structure. However, this engine was not put into practical use after its development.
On the other hand, Japanese patent publication No. 60-27732 discloses a single rotation rotary engine having a rotor holding bore in a housing, a rotor coaxial with the bore, a shaft member holding the rotor rotatably, three partition mechanisms (each having a movable partition plate and a spring member forcing the partition plate toward the rotation center), a cut-away portion formed by cutting away 1/3 of the rotor, a pressure reception surface directed radially at the leading end portion of cut-away portion, a compression surface formed arcuately at the bottom of cut-away portion, a suction port and an exhaust port positioned at both sides of the first partition mechanism on the lower left hand side portion of the housing, a compression port near the trailing side of second partition mechanism on the lower right hand side portion of the housing, an expansion port positioned near the leading side of third partition mechanism on the top portion of the housing, an ignition plug facing the expansion port, a gas passage pipe making the compression port communicate with the expansion port, etc.
Next, descriptions will be given concerning technical problems of above prior art. In various single rotation rotary engines 300A.about.300F shown in FIGS. 51-56, the axial center of the rotor is eccentric to the axial center of the rotor holding bore, and presumably some portion of the combustion gases will generate intrinsically a reversely driving torque. Thus, it is difficult to improve the efficiency in converting the combustion gas pressure into output torque. For an engine having plural cylinders, a straight type output shaft cannot be applied and, moreover, the structure of the output shaft becomes complicated.
Therefore, engine vibrations will occur due to this eccentric structure. It is also difficult to secure the durability of gas sealing members. Some of the above engines require an intake valve and an exhaust valve. It is also difficult to sufficiently lengthen the suction period and the exhaust period. In the single rotation rotary engine 300 shown in FIG. 57, the structure is complex due to its many components, and thus manufacturing costs become high. It seems difficult, therefore, to secure adequate durability. The single rotation rotary engine 300H shown in FIG. 58 is superior due to its simple structure, yet there remain some problems in the reliability and durability of gas sealing mechanisms between the cycloid tooth portions and small cylinders, and it is difficult to sufficiently lengthen the periods of suction stroke and exhaust stroke which are 180 degrees in the rotor rotation angle.
In the single rotation rotary engine disclosed in the Japanese patent publication noted earlier, a small amount of compressed fuel-air mixture remains continually in the communicating tube to supply the compressed mixture from the compression port to the combustion port. When a small-sized communicating tube is applied, the pressure loss of the compressed mixture will become large. Also, it is necessary to prevent the compressed mixture from firing in the tube by using a valve means. Because the reversely driving torque gradually increases during the combustion stroke, it is difficult to improve efficiency in converting the combustion gas pressure into output torque. Since the pressure reception surface of the rotor is directed radially, the partition plate cannot maintain any gas sealing contact with the rotor at high rotation speed. During the compression stroke, reversely driving torque due to negative pressure in the cut-away portion is generated presumably. Since each duration of the suction stroke, the compression stroke, the expansion stroke and the exhaust stroke is very short and runs at approximately 120 degrees in the rotor rotation angle, it is difficult to improve the engine's performance. The thin partition plates are not sufficient to permit gas seal engagements, and their durability is also insufficient. When the rotor housing is divided due to three partition plates, it will become difficult to fabricate the rotor housing and to secure precision in fabrication. Because three partition plates extend in a radial direction, engine size becomes large. As described above, the engine is not suitable for practical use due to these many shortcomings.
The objects of the present invention are as follows. One object is to improve efficiency in converting combustion gas pressure into output torque. Another object is to reduce the size and to simplify the engine structure. Other object is to lengthen the period during which the large pressure reception area is maintained. Other object is to reduce the pumping losses by securing the period of suction stroke and enlarging the period of exhaust stroke. A further object is to secure the performance of hermetically engaging contact and the durability of partitioning mechanisms partitioning between a bore surface and an outer circumferential surface of rotor. Still another object is to shorten the passage length of the gas passage mechanism which supplies compressed fuel-air mixture or compressed air from the suction chamber to the combustion chamber, and to simplify the structure of the gas passage mechanism. A final object is to make it possible to adopt a straight output shaft for an engine having plural cylinders.
According to one preferred embodiment of the present invention, a rotary piston type internal combustion engine comprises: a housing including a rotor housing and side housings; a cylindrical rotor holding bore formed in the housings; a rotor as a rotary piston held in the rotor holding bore rotatably around a rotation center which is an axial center of the rotor holding bore, the rotor including at a portion of its outer circumferential surface a minimum radius surface smaller in diameter than a bore surface which is a circumferential surface of the rotor holding bore, and including a projecting portion for partitioning whose top portion is in contact with the bore surface with gas seal engagement; an axial member coaxial with the rotor holding bore, the axial member supporting the rotor on the housing, and being rotatable in unison with the rotor; an intake port and an exhaust port which are formed in the housing, the exhaust port being positioned near the intake port on the trailing side in the direction of rotor rotation; a first partitioning means for partitioning hermetically between the outer circumferential surface of the rotor and the bore surface while engaging the outer circumferential surface, on an opposite side to the intake port and exhaust port with respect to the axial center of the rotor holding bore; a second partitioning means for partitioning hermetically between the outer circumferential surface of the rotor and the bore surface while engaging the outer circumferential face, between the intake port and exhaust port; and three chambers formed by partitioning with the first partitioning means, the second partitioning means and the projecting portion, between the outer circumferential surface of the rotor and the bore surface within the rotor holding bore, the three chambers varying their capacities according to rotor rotation.
According to certain preferred embodiments of the present invention, the rotor comprises, on its outer circumferential surface, the minimum radius face, a gently inclined curved pressurization surface extending from a trailing side end of the minimum radius surface to a top of the projecting portion, and a steeply inclined curved pressure reception surface extending from a leading side end of the minimum radius surface to the top of the projecting portion.
According to certain preferred embodiments of the present invention, the first partitioning means comprises: a first swinging partition member comprising an axial portion disposed so as to approximately circumscribe the bore surface and supported on the housing so as to swing around an axial center parallel to the axial center of the rotor holding bore, and a swinging partition plate formed integrally with the axial portion and extended by a given length from the axial portion in the direction of rotor rotation and having an engaging curved surface for engaging hermetically with the rotor; a first holding cavity formed in the rotor housing and being open to the bore surface, and being capable of holding the swinging partition plate of the first swinging partition member; and a first biasing means for forcing the first swinging partition member so that the swinging partition plate may be forced against the rotor.
According to certain preferred embodiments of the present invention, the second partitioning means comprises: a second swinging partition member comprising an axial portion positioned so as to approximately circumscribe the bore surface and supported on the housing so as to swing around an axial center parallel to the axial center of the rotor holding bore, and a swinging partition plate formed integrally with the axial portion and extended by a given length from the axial portion in the direction of rotor rotation, with an engaging curved surface for engaging hermetically with the rotor, the second swinging partition member being capable of opening and closing the intake port at timings depending on the rotation phase of the rotor; a second holding cavity formed in the rotor housing and being open to the bore surface, capable of holding the swinging partition plate of the second swinging partition member, and communicating with the intake port; and a second biasing means for forcing the second swinging partition member so that the swinging partition plate may be forced against the rotor.
According to certain preferred embodiments of the present invention, the three chambers comprise: when the projecting portion of the rotor is positioned on the leading side rather than the intake port and on the trailing side rather than the first partitioning means, a suction chamber communicating with the intake port, a compression chamber between the projecting portion and the first partitioning means, and an exhaust chamber communicating with the exhaust port; and when the projecting portion of the rotor is positioned on the leading side rather than the first partitioning means and on the trailing side rather than the exhaust port, a suction chamber or a compression chamber, an expansion chamber, and an exhaust chamber.
According to certain preferred embodiments of the present invention, the intake port and the exhaust port are formed in the rotor housing.
According to certain preferred embodiments of the present invention, the projecting portion of the rotor comprises a seal groove, a seal member fitted in the seal groove and being in hermetical contact with the bore surface of the rotor holding bore, and a biasing means forcing the seal member against the bore surface.
According to certain preferred embodiments of the present invention, the rotor housing is provided with a combustion subchamber opening to at least a portion of an interior end face of the first holding cavity, the combustion subchamber switchable between a closed condition closed hermetically by the swinging partition plate of the first swinging partition member and an opened condition opened to the first holding cavity and the expansion chamber.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises: a gas inlet passage formed in the first swinging partition member for introducing compressed fuel-air mixture or compressed air in the compression chamber into the combustion subchamber; and an opening/closing valve means having a valve shaft fitted in through an axial bore in the axial portion of the first swinging partition member, the opening/closing valve means opening and closing the gas inlet passage at timings depending on rotation phase of the rotor.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises: a subchamber forming member fitted in an axial bore in the axial portion of the first swinging partition member; and a combustion subchamber formed in the subchamber forming member.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises: a gas inlet passage formed in the first swinging partition member for introducing compressed fuel-air mixture or compressed air in the compression chamber into the combustion subchamber; a gas outlet passage formed in the first swinging partition member for expelling combustion gas from the combustion subchamber into the expansion chamber; and an opening/closing valve means having a valve shaft fitted in through the axial bore in the axial portion of the first swinging partition member, the valve shaft including the subchamber forming member, the opening/closing valve means opening and closing each of the gas inlet passage and the gas outlet passage at timings depending on rotation phase of the rotor.
According to certain preferred embodiments of the present invention, the first biasing means is constructed so as to provide an elastic force via one or more spring members.
According to certain preferred embodiments of the present invention, the first biasing means is constructed so as to provide an elastic force via one or more spring members and compressed air.
According to certain preferred embodiments of the present invention, the second biasing means is constructed so as to provide an elastic force of one or more spring members.
According to certain preferred embodiments of the present invention, the second biasing means is constructed so as to provide an elastic force of one or more spring members and compressed air.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises an oil supplying means for supplying lubricating oil to the engaging curved surface of the first swinging partition member of the first partitioning means.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises a cooling means for cooling the first swinging partition member of the first partitioning means.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises an oil supplying means for supplying lubricating oil to the engaging curved surface of the second swinging partition member of the second partitioning means.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises a cooling means for cooling the second swinging partition member of the second partitioning means.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises an ignition plug for igniting compressed fuel-air mixture in the combustion subchamber.
According to certain preferred embodiments of the present invention, the rotary piston type internal combustion engine further comprises a fuel injector for injecting fuel into the combustion subchamber.
Next descriptions will be made on the functions and advantages of above inventions.
According to certain preferred embodiments of the present invention, just as for the Wankel rotary piston engine, between the outer circumferential surface of the rotor and the bore surface within the rotor holding bore, three chambers whose respective capacities vary depending on rotor rotation, are formed by separating with the first partitioning means, the second partitioning means and the projecting portion of the rotor. When the rotor is in motion so that the projecting portion of the rotor has passed the intake port but not yet arrived at the first partitioning means, a suction chamber communicating with the intake port and expanding its capacity, a compression chamber between the projecting portion and the first partitioning means and reducing its capacity, and an exhaust chamber between first and second partitioning means and communicating with the exhaust port, are each formed. Additionally when the projecting portion of the rotor has passed the first partitioning means but not yet arrived at the exhaust port, the suction chamber or the compression chamber between the intake port and the first partitioning means, the expansion chamber between the first partitioning means and the projecting portion and an exhaust chamber between the projecting portion and the second partitioning means, are each formed. As the rotor rotates around the rotating center which is the axial center of the rotor holding bore, it is easy to attain hermetical sealing performance between the projecting portion and the bore surface and to attain durability of the hermetical sealing engagement. A lever length from an exerting position of resultant force of combustion gas pressure exerted on the rotor to the rotation center of rotor in the combustion stroke can be set large, and reversely driving torque by combustion gas pressure almost never be generated if the shape of rotor is formed properly. It is therefore possible to improve considerably the efficiency in converting the combustion gas pressure into output torque. By enlarging the circumferential length of the minimum radius surface of the rotor, or designing properly the shape of the outer circumferential surface portion of the rotor from the minimum radius surface to the projecting portion, it is possible to maintain an approximate maximum pressure reception area in the expansion stroke, and therefore it is possible to further improve the converting efficiency.
The rotor never rotates eccentrically, the axial member as an output shaft is coaxial to the axial center of the rotor holding bore, and thus a straight axial member can be used even in an engine having plural cylinders. Vibrations due to eccentric configuration will not be generated. The suction stroke begins just after the projecting portion of the rotor passes the intake port and continues until a certain timing (depending on the shape of rotor) after the projecting portion passes the first partitioning means. In this way suction stroke duration becomes sufficient and suction resistance can be reduced. The exhaust stroke begins after the projecting portion passes the exhaust port and continues while the rotor rotates almost one revolution. Thus the duration of the exhaust stroke becomes sufficient and it becomes unnecessary to provide an exhaust valve means in the exhaust port. As a result, exhaust resistance can be reduced considerably. Accordingly, the pumping loss due to suction and exhaust can also be reduced considerably.
According to certain preferred embodiments of the present invention, the rotor comprises, on its outer circumferential surface, the minimum radius face, the gently inclined curved pressurization surface extending from the trailing side end of the minimum radius surface to the top of the projecting portion, and the steeply inclined curved pressure reception surface extending from the leading side end of the minimum radius surface to the top of the projecting portion. Thus, when the rotor rotates, the first partitioning means or the second partitioning means is passed first by the gently inclined curved pressurization surface, followed by the top of the projecting portion, and finally by the steeply inclined curved pressure reception surface. Accordingly, motion of the first and second partitioning means and the rotor become smooth, and reversely driving torques due to pressing forces by the first and second partitioning means become negligible. And that, when the steeply inclined curved pressure reception surface receives combustion gas pressure, the increasing speed of the pressure reception area becomes sufficient, and thereby the output torque in the expansion stroke increases rapidly so that the converting efficiency become considerable.
According to certain preferred embodiments of the present invention, the first partitioning means comprises the first swinging partition member, the first holding cavity and the first biasing means. The first swinging partition member comprises the axial portion which is positioned so as to approximately circumscribe the bore surface and supported on the housing rotatably around the axial center parallel to the axial center of the rotor holding bore, and the swinging partition plate formed integrally with the axial portion and extending by a given length from the axial portion in the direction of rotor rotation and having the engaging curved surface engaging hermetically with the rotor. The first swinging partition member is enforced toward the rotor by the first biasing means. This first biasing means can be constructed of one or more spring members. Furthermore, although the gas pressure of compressed fuel-air mixture or compressed air is exerted on the swinging partition plate of the first swinging partition member, the first biasing means enforces the first swinging partition member toward the rotor so that the swinging partition plate may stay in contact with the rotor. Because the axial portion circumscribes approximately the bore surface and the swinging partition plate extends by a given length from the axial portion toward the rotor rotation direction, the compression chamber can compress fuel-air mixture or air until its capacity becomes sufficiently small. And, in accordance with rotor rotation, while the engaging curved surface of the swinging partition plate stays in contact with the rotor, the first swinging partition member swings around the center of the axial portion with following the rotor. Accordingly, as the swinging partition plate swings around the center of the axial portion in accordance with the rotor rotation, the contact area of the engaging curved surface oscillates, and therefore local abrasion almost never occurs in the engaging curved surface,improving the gas seal function and securing the durability.
When the projecting portion of the rotor passes the first partitioning means, the swinging partition plate of the first swinging partition member is held in the first holding cavity opened to the bore surface, allowing the rotor to rotate without hitting the swinging partition plate. When the swinging partition plate is held in the cavity, the projecting portion of rotor stays in contact with the swinging partition plate. As a result, jumping of the swinging partition plate does not occur. The first swinging partition member does not project largely outside of the rotor housing. Although the first swinging partition member swings, the partition member occupies only a small space. In this way, the rotor housing can be reduced in size and it becomes unnecessary to divide the rotor housing into plural pieces to provide the first swinging partition member.
According to certain preferred embodiments of the present invention, the second partitioning means comprises the second swinging partition member, the second holding cavity and the second biasing means. The second swinging partition member comprises the axial portion positioned so as to approximately circumscribe the bore surface and supported on the housing rotatably around the axial center parallel to the axial center of the rotor holding bore, and the swinging partition plate formed integrally with the axial portion and extended by a given length from the axial portion toward the direction of rotor rotation, having an engaging curved surface which engages hermetically with the rotor. This second swinging partition member is constructed so as to open and close the intake port at timings determined by rotor rotation. The second swinging partition member is enforced toward the rotor by the second biasing means. This second biasing means can be constructed with one or more spring members, and generates the biasing force to prevent the swinging partition plate from detaching from the rotor when exhaust gas pressure in the exhaust chamber is exerted on the partition plate.
Because the axial portion circumscribes approximately the bore surface and the swinging partition plate extends by a given length from the axial portion toward the rotor rotation direction, the exhaust chamber can be reduce in size until its capacity becomes sufficiently small. As well, in accordance with rotor rotation, while the engaging curved surface of the swinging partition plate stays in contact with the rotor, the second swinging partition member swings around the center of the axial portion so as to follow the rotor. Accordingly, as the swinging partition plate swings around the center of the axial portion in accordance with rotor rotation, the contact area of the engaging curved surface oscillates, and therefore local abrasion does not occur in the engaging curved surface, allowing for improved gas seal function and durability.
When the projecting portion of the rotor passes the second partitioning means, the swinging partition plate of the second swinging partition member is held in the second holding cavity open to the bore surface. The rotor can thereby rotate without colliding against the swinging partition plate. When the swinging partition plate is held in the cavity, the projecting portion of the rotor stays in contact with the swinging partition plate and so jumping of the swinging partition plate does not occur.
The intake port is opening to the second holding cavity, and the second swinging partition member opens and closes the intake port at timings depending on rotor rotation. Accordingly, the second swinging partition member operates as an opening/closing valve means for opening and closing the intake port, and compared with the instances when an opening/closing valve means is provided independently, this structure can be simplified. The second swinging partition member does not project largely outside of the rotor housing. Although the second swinging partition member swings, the partition member occupies only a small space. Thereby, the rotor housing can be reduced in size and it becomes unnecessary to divide the rotor housing into plural pieces to provide the second swinging partition member.
According to certain preferred embodiments of the present invention, the three chambers comprises, when the projecting portion of the rotor is positioned on the leading side than the intake port and on the trailing side than the first partitioning means, the suction chamber communicates with the intake port, the compression chamber is located between the projecting portion and the first partitioning means, and the exhaust chamber communicates with the exhaust port. Where the projecting portion of the rotor is positioned on the leading side than the first partitioning means and on the trailing side than the exhaust port, the three chambers are made up of the suction chamber or the compression chamber, the expansion chamber, and the exhaust chamber. Here, the suction chamber is partitioned between the second partitioning means and the steeply inclined curved pressure reception surface of the rotor. The capacity of the suction chamber in the early stage of suction stroke increases rapidly. This improves the charging efficiency. The capacity of the suction chamber can also be enlarged. As the expansion chamber is partitioned between the first partitioning means and the steeply inclined curved pressure reception surface of the rotor, the ascension of output torque in the expansion stroke can be promoted. In addition, the capacity of expansion chamber can be enlarged, and the pressure reception area of the rotor facing the expansion chamber can be enlarged. As the compression chamber is partitioned between the gently inclined curved pressurization surface of the rotor and the first partitioning means, the duration of the compression stroke can be lengthened so that compression operation becomes smooth. As the exhaust chamber is partitioned between the gently inclined curved pressurization surface of the rotor and the second partitioning means, exhaust operation also becomes smooth.
According to certain preferred embodiments of the present invention, the intake port and the exhaust port are provided in the rotor housing. However, by setting the length of these ports along the axial direction of the rotor to be shorter than that of the rotor, it is possible to prevent the rotor housing from being divided by these ports. Because these ports are provided in the rotor housing, the structures of these ports and the side housing can also be simplified.
According to certain preferred embodiments of the present invention, the projecting portion of the rotor comprises the seal groove, the seal member, as well as the biasing means biasing the seal member against the bore surface. Therefore the projecting portion of the rotor can partition hermetically between a pair of neighboring chambers.
According to certain preferred embodiments of the present invention, the combustion subchamber is formed in the rotor housing so as to open to at least a portion of the interior end face of the first holding cavity, and the combustion subchamber can be switched between the closed condition closed hermetically by the swinging partition plate of the first swinging partition member and the opened condition opened to the first holding cavity and the expansion chamber. Thus, the first swinging partition member is utilized as the opening/closing valve means for opening and closing the subchamber. Accordingly, in comparison with the case where an opening/closing valve means is provided independently, the structure can be simplified, and it becomes unnecessary to provide an actuator for driving the opening/closing valve means. After the subchamber is closed by the swinging partition plate in the late stage of the compression stroke, the gas pressure of the compressed fuel-air mixture or compressed air in the subchamber is exerted on the swinging partition plate, and therefore it is possible to reduce the maximum value of biasing force of the biasing means for resisting the compressed fuel-air mixture or compressed air.
The subchamber is opened and closed by the swinging partition plate which swings around the center of the axial portion near the bore surface, thereby it is possible to enlarge the opening area when the subchamber is open. In such cases, the combustion gas pressure is exerted on the swinging partition plate so as to enforce it against the rotor, thereby sealing performance (partition function) sealing hermetically by the first partitioning means becomes complete. Furthermore, the swinging partition plate extends by a given length in the direction of rotor rotation, and the subchamber is opened just after the rotor has passed the partition plate. Therefore, a compressed fuel-air mixture or compressed air is held in the subchamber during a short period, and thus firing performance can be enhanced and initial combustibility in the expansion stroke can be enhanced.
According to certain preferred embodiments of the present invention, the engine has the gas inlet passage for introducing the compressed fuel-air mixture or compressed air in the compression chamber into the subchamber and the opening/closing valve means for opening and closing the gas inlet passage at timings depending on the rotation phase of the rotor. The gas inlet passage is provided in the first swinging partition member, and the opening/closing valve means has the valve shaft fitted through in the axial bore formed in the axial portion of the first swinging partition member. The gas inlet passage can therefore be made short, allowing for the passage area of gas inlet passage to be enlarged as required. Furthermore, the opening/closing valve means can be constructed as a rotary valve including the valve shaft, allowing the structure of the valve means to be simplified and the valve shaft to be constructed as a common valve shaft for plural cylinders. It is also possible to drive the common valve shaft synchronously with the rotor.
According to certain preferred embodiments of the present invention, the subchamber forming member is fitted in the axial bore in the axial portion of the first swinging partition member, and the combustion subchamber is formed in the subchamber forming member. In this way, the distance from the compression chamber to the subchamber (i.e. length of gas inlet passage) can be minimized. As well, the residual quantity of compressed fuel-air mixture or compressed air residing in the gas inlet passage can be minimized and the structure of the subchamber can be simplified.
According to certain preferred embodiments of the present invention, the gas inlet passage for introducing the compressed fuel-air mixture or compressed air into the combustion subchamber, as well as the gas outlet passage for feeding out the combustion gas from the combustion subchamber into the expansion chamber are provided. In addition, the opening/closing valve means for opening and closing each of the gas inlet passage and the gas outlet passage at timings depending on the rotation phase of the rotor is also provided. The opening/closing valve means has the valve shaft fitted in through the axial bore in the axial portion of the first swinging partition member, and the valve shaft has the subchamber forming member. The opening/closing valve means opens and closes each of the gas inlet passage and the gas outlet passage at timings depending on the rotation phase of the rotor. Thereby, the structure of opening/closing valve means can be simplified remarkably, and the structure of rotor housing can be simplified.
According to certain preferred embodiments of the present invention, the first biasing means for enforcing the first swinging partition member of the first partitioning means is constructed so as to enforce by elastic force of one or more spring members. In this way, the structure of biasing means can be simplified.
According to certain preferred embodiments of the present invention, the first biasing means is constructed so as to enforce by elastic force of one or more spring members and compressed air, allowing a strong biasing force to be generated and a rapid response to be attained.
According to certain preferred embodiments of the present invention, the second biasing means for enforcing the second swinging partition member of the second partitioning means is constructed so as to enforce by elastic force of one or more spring members, allowing the structure of the biasing means to be simplified.
According to certain preferred embodiments of the present invention, the second biasing means is constructed so as to enforce by elastic force of one or more spring members and compressed air, allowing a strong biasing force to be generated and a rapid response to be attained.
According to certain preferred embodiments of the present invention, the oil supplying means supplies oil to the engaging curved surface of the first swinging partition member of the first partitioning means, making it possible to lubricate certainly between the rotor and the engaging curved surface.
According to certain preferred embodiments of the present invention, the cooling means cools the first swinging partition member of the first partitioning means, preventing overheat of the first swinging partition member and also assuring durability. The oil supplying means supplies oil to the engaging curved surface of the second swinging partition member of the second partitioning means, making it possible to lubricate certainly between the rotor and the engaging curved surface.
According to certain preferred embodiments of the present invention, the cooling means cools the second swinging partition member of the second partitioning means, preventing overheat of the second swinging partition member and also assuring durability.
According to certain preferred embodiments of the present invention, the ignition plug for igniting the compressed fuel-air mixture in the combustion subchamber is provided, and thus this engine is an ignition type internal combustion engine in which a mixed gas of air and fuel, such as gasoline, is ignited. In this engine, a compressed fuel-air mixture of approximate compression ratio from 8 to 10 is charged from the compression chamber into the subchamber. After closing the gas inlet passage by the opening/closing valve means, the ignition plug ignites, and then firing of the mixture spreads to the subchamber. After the projecting portion of the rotor passes the first partitioning means, the subchamber is opened and the combustion gas is injected into the expansion chamber from the subchamber, as the combustion gas pressure is exerted on the steeply inclined curved pressure reception surface of the rotor, enabling the rotor to rotate.
According to certain preferred embodiments of the present invention, the fuel injector for injecting fuel into the combustion subchamber is provided, and thus this engine is a compression ignition type internal combustion engine in which ignition is made by injecting fuel such as right oil, into the compressed air in the subchamber. The compressed air of an approximate compression ratio 14 is charged from the compression chamber into the subchamber. After closing the gas inlet passage by the opening/closing valve means, the fuel injector injects fuel, and then compression ignition occurs in the subchamber.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings illustrating preferred embodiments of the invention.